I think the hate Last Jedi receives is overblown BUT it was trash. I was semi hopeful after TFA (in hindsight it set the groundwork for a lot of the bad parts) and forgave it some of its flaws due to being the forst movie in a while and having to restart the franchise when it came to theaters but I walked out of TLJ and wanted my time back.
I think there is a lot of hate for Rey that’s actual misogyny hidden behind the legitimate criticism. But the characters writing doesn’t help that situation. I don’t think any of the other characters are written much better so the fact Rey ends up getting most of the hate boils down to her being a woman and her being the main character (I cannot even guess which of these two weighs more into that equation, which is a shame. Her being female really shouldn’t factor into this). The entire movie just felt very silly to me. It makes for good eye candy but if you think deeper about anything that could be construed as a message in that movie it just falls apart imo.
Tl;dr: I don’t think it should come as a shock that the movoe got hate, it was pretty bad all things considered, but the amount sure was shocking